Electronics 2 Flashcards
(21 cards)
What are the stages of an Instrumentation System?
Measurand - Transducer - Amplifier - Filter - ADC - Output
What is a Measurand?
A physical quantity that is measured by a system.
E.g. Distance, Temperature, Pressure…..
What is a Transducer?
In principle a Transducer is a device that converts one type of energy to another. Commonly implies use as a sensor/detector that converts the measurand into a signal.
How can a signal be changed during the measurement process or afterwards adding noise to the signal?
1- Signal Distortions
2- Random noise, such as thermal noise
3- interference
4- Environmental Effects such as drift
What are the processes that can be used to manipulate a signal?
1- Amplification 2- Filtering 3- Conversion 4- Modulation 5- Differentiation 6- Integration 7- Rectification
What are some Electrical Transducers?
Resistive, Capacitive, Inductive, Digital
What do Resistive Transducers do?
Change the ratio between voltage and current.
What do Capacitive Transducers do?
Store Energy in an Electric Field.
What do Inductive Transducers do?
Inductors store energy in magnetic fields.
Changes to the magnetic fields can change the impedance of an inductor.
What do Digital Transducers do?
Digital transducers give an ON/OFF response.
Can be a single response or several parallel or serial responses.
What are the properties of a measurement system?
Advantageous: Reliability, Stability, Linearity, Fast Response, Ease of Calibration.
Disadvantageous: Drift, Noise, Hysteresis, Inertia, Frequency Response.
What is Full Scale Output (FSO) ?
The range over which the output signal can swing.
What is error ?
Deviation Between real and measured value or theoretical relationship between input and output.
What is accuracy ?
The sum of all possible errors that are likely to occur.
What is span ?
The difference between the limits of range.
What is sensitivity ?
The amount of output per input.
What is resolution ?
The minimum change of input to change the output.
What is response time?
The time it takes to achieve 95% of steady state value (SSV) after a change.
Technically most changes are asymptotic- never reach steady state- hence the 95%.
What is Hysteresis ?
The difference in output of a transducer if a value is approached from different directions.
What is a non-linearity error?
Error between linear and real behaviour in a sensor.
What are the key parts of an instrumentation system block diagram?
1- Sensors
2- Signal Conditioner
3- Display
